Room to breathe — time to take clean indoor air as seriously as we take clean water

Two hundred years ago, drinking water from a water pump could have been lethal. The water might have appeared clean but could be contaminated with sewage, causing a serious and often deadly diarrhoeal disease owing to cholera. Luckily, societal norms and regulations around water and sanitation have shifted. We now expect the water from our taps to be clean and safe. 

Although we now have safer drinking water, we have a challenge ahead to do the same for the indoor air that we breathe and share. 

The Covid-19 pandemic has had a devastating impact on tuberculosis (TB) care in South Africa and globally, with TB-related deaths increasing for the first time in a decade. However, since Covid-19 and TB are both airborne infections, the attention surrounding mitigation measures could provide a glimmer of hope for the TB response. 

Much of this synergy has focused on mask-wearing, which can reduce the risks of transmission of both Covid-19 and TB that result from exposure to shared air. Mask-wearing has gained traction and some level of acceptance during the ongoing Covid-19 pandemic. 

Yet there has been inadequate prioritisation of the need to improve the safety of our shared air. This is particularly important in crowded indoor settings that pose the highest risk of transmission and requires dedicated efforts, resources, and policy changes to improve indoor ventilation.   

We have known for years that increasing natural ventilation by opening doors and windows is an effective strategy to increase the volume of fresh air that enters from the outdoors. In South Africa, we are fortunate to have weather that allowed us to use natural ventilation frequently. However, the Covid-19 pandemic has brought attention to settings that are difficult to ventilate — due to building infrastructure or when the weather becomes colder. 

Many tools available

Yet there are many tools to improve ventilation that we have not used optimally. This includes high-efficiency particulate air (Hepa) filtrations, Carbon Dioxide (CO2) monitors, and germicidal ultraviolet disinfection technology. During the Covid-19 pandemic, a do-it-yourself (DIY) cost-effective air filter, known as the Corsi-Rosenthal Box, has gained traction both as a school project and a convenient solution to improve indoor air quality, with research showing it can be an effective tool to reduce aerosol hazards in indoor spaces. This DIY air filter takes about 45-minutes to make and only requires a box fan, duct tape, four Hepa air filters, and cardboard. 

While the world of Hepa filters can offer a dizzying array of options (some that fall firmly in the snake oil category) — a non-profit public service known as Clean Air Stars has developed an air filter recommendation tool that evaluates the acceptable noise level, Wi-Fi requirements, room volume, and filter requirements to ensure that an adequate number of Hepa filters are provided to ensure effective filtration and to reduce the transmission of airborne diseases. They have also developed a repository for businesses that have taken steps to make their shared air safer. 

CO2 monitors could also be an important tool to help evaluate the ventilation quality of indoor facilities and spur further action to improve ventilation. Higher CO2 levels, particularly if they reach over 1,000-1,500 parts per million (ppm), show that there is likely a build-up of rebreathed air that indicates poor ventilation. 

A study conducted in South Africa using CO2 monitors demonstrated the important point that air conditioners, unlike other strategies to cool the air such as opening a window, do not provide outdoor air exchange and lead to a build-up of CO2 indoors when doors and windows are closed, thereby decreasing ventilation. 

Increased use of measures such as germicidal ultraviolet (GUV) disinfection holds promise to clear the air of potential pathogens. Guidelines have been developed for the use of GUV, based on key studies conducted in South Africa, but they have not been released and there is still a moratorium on the implementation of GUV fixtures in healthcare facilities after previous unregulated use did not have adequate maintenance and oversight.  

Healthcare workers at risk

Even prior to the Covid-19 pandemic, we have known that there is an urgent need to improve ventilation in healthcare settings as healthcare workers are three times more likely than the general population to develop drug-sensitive TB and six times more likely to develop drug-resistant TB. Poor ventilation in overcrowded indoor spaces such as health facilities is recognised as an important risk factor for TB transmission. A recent study conducted in South Africa using small, portable CO2 monitors worn by health workers during their work shifts showed that health workers who experienced higher average CO2 levels had a higher risk of developing TB infection. Yet, the Occupational Health Policy for Health Workers regarding TB and HIV, drafted in 2016, that has far-reaching recommendations for addressing this occupational risk has still not been released. 

The authors say there is an urgent need to improve ventilation in healthcare settings. (Photo by Gallo Images/Papi Morake)